1. Field of the Invention
The present invention relates generally to a refrigerating cycle apparatus with a compressor having two compressor means in a sealed casing, and more particularly to an improvement of the structure for feeding/discharging a refrigerant gas into/from each compressor means.
2. Description of the Related Art
A refrigerating cycle apparatus comprises a compressor for sucking and compressing a refrigerant gas; a condenser for condensing and liquefying the refrigerant gas pressurized by the compressor; a pressure-reducing device for reducing the pressure of the refrigerant liquefied by the condenser; and an evaporator for evaporating the pressure-reduced liquid refrigerant, which has been pressure-reduced by the pressure-reducing device, thus effecting a refrigerating operation. These elements are successively connected via a refrigerant pipe.
The compressor may have various structures. According to one of the structures, two compressor means are contained in a sealed casing, and these two compressor means are connected to, and driven simultaneously by, a single motor unit.
For example, Published Examined Japanese Utility Model Application No. 62-30693 discloses a refrigerating cycle with a compressor having two compressor means.
This refrigerating cycle employs a higher-stage injection system wherein an intermediate economizer in a two-stage compressor is simplified. The advantage of this cycle is the protection of the higher-stage part.
However, in a compressor required in a cooling cycle apparatus, a wide range of refrigerating cycle loads are applied. It is thus required that the refrigeration capacity of the compressor be variable. In this respect, the two-stage compression compressor is not satisfactory.
Under the situation, for example, Published Unexamined Japanese Patent Application No. 63-212797 proposed a compressor wherein first compressor means and second compressor means having two cylinders (large and small cylinders) with different compression volumes are housed within a sealed casing.
Gas opening/closing means is provided at the suction side and discharge side of each compressor means, and the two gas opening/closing means are connected via a refrigerant pipe.
The first and second compressor means are driven simultaneously. The gas opening/closing means are switched to provide three drive modes: 1) independent compression drive mode in which the large and small cylinders (two cylinders) perform compression operations independently, 2) parallel compression drive mode in which the cylinders perform compression operations in parallel, and 3) series-compression drive mode in which the compression operation is performed over two stages from one cylinder to the other cylinder.
With this compressor, the range of variable capacity is remarkably increased, and the requirements for refrigerating cycle loads over the almost entire range can be satisfied.
In the above compressor, however, the number of gas opening/closing means is large, and the control means for controlling the gas opening/closing means is complicated accordingly.
In addition, because of many gas opening/closing means, the pipe for connecting them becomes longer, and the size of the entire apparatus is increased.